The mini-heatwave that settled upon many parts of the UK in June provided a welcome reminder that hot, sunny weather wasn’t necessarily the preserve of our compatriots across the continent. Sweltering temperatures, however pleasant they might be for camels or ice cream vendors, do not make ideal building conditions, particularly when it comes to concreting.

For concrete to be placed and finished correctly, it needs to remain workable. In hot weather, moisture is drawn from the mixture more quickly, which can lead to it setting too rapidly for the user’s requirements. For instance, a 300mm-thick slab requires two loads of concrete to fill a mould.

Timings are tight, and it’s not unknown for the first load to set before the second load is even delivered – particularly during hot weather. It only takes the second delivery load to be delayed by traffic, for example, for the process to fail. Fresh cement that’s poured onto an already-set and compacted base can lead to cold joints and unevenness.

Fresh loads of cement should knit together to form one homogenous mass. For this to happen – concrete generates its own heat, so climatic conditions are only part of the hydration issue – it helps if the setting process is decelerated. Here’s where the availability of a product range such as Sikatard is such a huge benefit.

Sikatard is an admixture in liquid form developed for the control of cement hydration. It coats the cement particles to prevent infusion and slow the drying-out process. This ensures the concrete mix is stabilised and prevents its setting for hours or even days. Sikatard, which conforms to the requirements of BS EN 934-2 Table 8, can also be used in steel reinforced concrete construction without restriction. Its stabilising properties ensure the distribution of stresses throughout the reinforcement encapsulated in the concrete isn’t compromised.

Sika PilePak is another product proven to eliminate moisture escape from concrete. Its use during cast in situ concrete piling projects eases steel reinforcement fitting. Sika PilePak acts as a thickening agent which helps retain moisture within the concrete’s cement paste. It’s added to the concrete during batching then delivered to site.

Dry or gravel-based ground absorbs water from cement like a sponge, making steel reinforcement insertion incredibly difficult, which could affect the concrete, and ultimately, the infrastructure’s stability. Sika PilePak ensures consistency and workability of the concrete over a prolonged period of time, helping avoid any concrete problems at any one pile position.

With the government announcing a total of 250,000 new homes are needed annually to keep pace with demand, speed is key to developers helping fulfil this requirement without compromise to safety or quality. Thankfully, in Sika PilePak and the Sikatard range, the industry has the products with which to build a stable base to help meet our future housing needs – however hot the weather.

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The seaside is known to do wonders for a person’s health, but it does nothing for the long-term wellbeing of buildings. The main cause of deterioration of reinforced concrete structures is the corrosion of embedded steel, particularly when exposed to chlorides found in sea water and airborne salts. This impacts on buildings within marine environments such as jetties, ports and bridges.
Reinforced concrete structures are built to last and can generally expect to have a lifespan of about 50 years. However, in areas of chloride ingress the rate of corrosion increases, as does the need for repairs to maintain the buildings. Without professional treatment, a concrete’s surface can crack and spall.
This is caused by passivating iron oxides, which protect the steel reinforcement, being destroyed by chlorides in air and water. The resulting surface debilitation could potentially weaken the structure and leave it vulnerable to serious deterioration – even collapse. This is particularly pertinent to public infrastructure such as bridges, which could be subject to lengthy and costly repairs funded by already cash-strapped local authorities. In such instances, people’s daily lives might also be severely disrupted.
The same applies to jetties, which serve vital aesthetic and operational purpose for marinas and nearly 100 sea ports across the UK. They also offer frontline sea defence, but bear the brunt of chloride’s invasive effects on account of being situated in tidal zones or splash areas.
Sacrificial efficiency
Sika was recently selected to supply a concrete repair and total corrosion management system (TCM) to the underside of a dockside quay that had displayed signs of corrosion due to chloride contamination. Sika® Galvashield®galvanic, sacrificial anodes, which are proven to provide long-term protection to high chloride environments, were installed as part of the refurbishment.
The sacrificial anodes, comprising a zinc core encased in a small, cementitious shell, are installed within repair sites to prevent incipient anodes developing, or outside repaired sites to protect the reinforcement in chloride-infused concrete. Easily fastened to exposed steel reinforcement – or into cored and grouted holes in the concrete outside the repair site – the anode’s zinc core corrodes sacrificially to protect the surrounding rebar and prevent formation of new corrosion sites adjacent to repairs. This sacrificial zinc approach is similar to protecting oil rigs & hulls of ships.
All-in-one solution
As there is no need for an external power source, Sika’s galvanic systems are a popular choice for effective, low maintenance corrosion mitigation. Unlike other manufacturers, Sika provides repair materials and coatings as part of a total corrosion management package, because as well as supplying the anode, we provide repair materials and coatings. Once repairs have been carried out to all parties’ satisfaction, we will guarantee the repair system for up to 20 years – an offer unique to Sika.
Galvanic anodes have revolutionised the treatment of chloride-contaminated concrete. It’s a system that is ingenious in its simplicity and effectiveness; eradicating the need for costly, time-inefficient and energy-consuming shot-blast methods of corrosion removal. The anode system is a smart 21st century solution to an age-old problem. It means our weathered, waterfront buildings can stand protected – ‘the seas shall not have them’.
By Ronnie Turner, Infrastructure Manager - Refurbishment at Sika UK

The mini-heatwave that settled upon many parts of the UK in June provided a welcome reminder that hot, sunny weather wasn’t necessarily the preserve of our compatriots across the continent. Sweltering temperatures, however pleasant they might be for camels or ice cream vendors, do not make ideal building conditions, particularly when it comes to concreting.
For concrete to be placed and finished correctly, it needs to remain workable. In hot weather, moisture is drawn from the mixture more quickly, which can lead to it setting too rapidly for the user’s requirements. For instance, a 300mm-thick slab requires two loads of concrete to fill a mould.
Timings are tight, and it’s not unknown for the first load to set before the second load is even delivered – particularly during hot weather. It only takes the second delivery load to be delayed by traffic, for example, for the process to fail. Fresh cement that’s poured onto an already-set and compacted base can lead to cold joints and unevenness.
Fresh loads of cement should knit together to form one homogenous mass. For this to happen – concrete generates its own heat, so climatic conditions are only part of the hydration issue – it helps if the setting process is decelerated. Here’s where the availability of a product range such as Sikatard is such a huge benefit.
Sikatard is an admixture in liquid form developed for the control of cement hydration. It coats the cement particles to prevent infusion and slow the drying-out process. This ensures the concrete mix is stabilised and prevents its setting for hours or even days. Sikatard, which conforms to the requirements of BS EN 934-2 Table 8, can also be used in steel reinforced concrete construction without restriction. Its stabilising properties ensure the distribution of stresses throughout the reinforcement encapsulated in the concrete isn’t compromised.
Sika PilePak is another product proven to eliminate moisture escape from concrete. Its use during cast in situ concrete piling projects eases steel reinforcement fitting. Sika PilePak acts as a thickening agent which helps retain moisture within the concrete’s cement paste. It’s added to the concrete during batching then delivered to site.
Dry or gravel-based ground absorbs water from cement like a sponge, making steel reinforcement insertion incredibly difficult, which could affect the concrete, and ultimately, the infrastructure’s stability. Sika PilePak ensures consistency and workability of the concrete over a prolonged period of time, helping avoid any concrete problems at any one pile position.
With the government announcing a total of 250,000 new homes are needed annually to keep pace with demand, speed is key to developers helping fulfil this requirement without compromise to safety or quality. Thankfully, in Sika PilePak and the Sikatard range, the industry has the products with which to build a stable base to help meet our future housing needs – however hot the weather.
By John Eustace, Product Manager at Sika

It took about 50 years for television to transform from black and white to glorious technicolour; the availability of pigmentation to give concrete shades other than grey took infinitely longer writes Lee Baldwin, Product Development Manager at Sika. The wait was worth it, however, as the colourisation of this otherwise drab-looking material has given it a new lease of life in terms of its usage; brightening our commercial and domestic worlds in the process.
From industrial units to art installations, coloured concrete has become a go-to solution for designers and the like who want their structures to look good as well as last. For the past 15 years or so, Sika has been among those leading the way in the development of the precious pigment that has allowed concrete structures be seen in a different light… and shade. The colourisation process involves adding liquid or powder-form pigmented metal oxides - mainly iron oxide – to a concrete mix. The dosage is normally 0.5 – 5.0% of the cement weight. Higher dosages do not enhance the colour intensity but may adversely affect the concrete quality. A range of primary colours are available such as yellow, red, black and white, which can be used to create a spectrum of shades.
No limits
With concrete now able to sport coats of many colours there is no limit to how and where it can be used, dependent on whether it is designed to stand-out or blend-in with its environment. A good example of pigmented concrete’s harmonious capabilities can be seen at Payers Park, Folkestone where it was used in the formation of sandstone-coloured steps as part of a recent Sika-based project. The same properties also saw Sika’s colour range bring a certain gravitas and style to a humble seaside public toilet, which was deemed so at one with its coastal surroundings, the installation won a design award. Other recent commercial projects to benefit Sika Coloured Concrete include specification at the new Concorde Museum in Bristol, where it will be used to create dark grey flooring – a perfect accompaniment to the brilliant white supersonic plane it is to support. It’s also been selected as a colourful base for a skate park, the bright shades and tones in-keeping with the lively, fun-packed environment.
Solid alternative
Pigmented concrete is also gaining favour as a domestic installation. Its durable, maintenance-free properties have led to its specification for driveways as a more solid alternative to tarmac. Chips and minor damaging to coloured concrete does little to spoil its look. The pigment runs throughout the concrete, therefore the surface and the underlying colour is the same. Kitchens, where coloured concrete creates hard, marble-like flooring, are also ideal. Sika Coloured Concrete was also used to create an attractive art installation at Queen Elizabeth Park in London.
Pigmentation has added a new flexibility to concrete, this most unyielding of materials. Its grey days are over and a brighter, more colourful new era awaits.
Visit www.sika.co.uk.

For eighteen years, Sika® Galvashield® Anodes have been successfully employed to prevent corrosion in reinforced concrete. The method behind the solution, however, was devised a long time before then - 194 years to be precise.
In 1824, Sir Humphrey Davy deduced the simple principle of a sacrificial anode for the Royal Navy, which has led to the development of management systems as a time and cost-effective solution for concrete structures at high risk of corrosion.
HISTORY
Galvanic anodes for reinforced concrete structures were developed in the late 1990s and are produced from zinc encased in a formulated porous cementitious mortar surrounded by a specifically developed activator with a pH>14.5. Their manufacture has proved a major success in the treatment of chloride-induced corrosion of steel reinforcement in concrete structures. Chlorides can be introduced into the concrete in multiple ways: cast in during construction; use of sea dredged aggregates, chemical works and deicing salts or seawater leading to the localized breakdown of the normally passive steel reinforcement in the form of pitting corrosion.
In structural trials at sites across the UK, zinc galvanic anodes were shown to be successful in providing adequate cathodic current to the steel reinforcement around the periphery of a patch repair for a period of 18.5 years and continue to work. The process involves the activation of the anode’s sacrificial zinc core by the surrounding specially-formulated cementitious mortar. The anode is quickly and easily fastened to the exposed reinforcing steel, and once installed, corrodes preferentially to the surrounding rebar. The system, which contains integral lead wires, can be targeted at specific high-corrosion risk areas within structures or over large areas for widespread corrosion protection and control.
Patch repair alone is a less reliable solution than total corrosion management, as its long-term effectiveness is hampered by the prevalence of chlorides in other areas of the concrete. Whilst removing and making good the most visibly spalled section of the structure might initially appear to resolve the issue, the repair of sites which are actively corroding in a chloride-contaminated structure is likely to stimulate corrosion at sites adjacent to the repair – a phenomenon known as the incipient anode, ring anode or halo effect.
REPAIR AND RESIST
Therefore, a long-term management solution that includes Sika® Galvashield® XP - which comprises embedded galvanic anodes - addresses the source of the corrosion and is a far more cost-effective repair solution as it minimizes ongoing maintenance costs and extends the life of the structure. Galvanic anodes can eliminate the need for long-term power supplies and control equipment to ensure low-running costs and an attractive option for remote structures. They can also negate the need to break-out large areas of contaminated concrete, reducing environmental disruption and the need for structural propping.
A zinc core encased by a small, cementitious shell, Sika® Galvashield® sacrificial anodes might not demonstrate a particularly dynamic presence, but they’ve proved a mighty effective weapon against the corrosive elements which threaten the structural integrity of concrete structures the world over.
Visit: https://gbr.sika.com/en/group.html

Jul 25, 2018 0

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